This invention concerns an active circuit composed of insulated gate field effect transistors (FET), integrated within the same substrate, containing at least one amplification stage that includes a transistor amplifier whose source constitutes the junction of the input and output circuits of the amplifier stage, these circuits being capacitively coupled with the gate and the drain of the transistor amplifier, the drain of this transistor being connected to a current source that furnishes a current I.sub.D1.
The known integrable active circuits employing negative feedback in an amplifier stage, e.g., by using a resistor made of slightly doped polycrystalline silicon (Swiss patent application number 11788/74) or a band pass gate (U.S. Pat. No. 3,753,154) present the serious drawback of not permitting precise control of the amplifier characteristics. In particular, gain, power consumption, input and output resistance and frequency limits vary from one series of circuits to another and even from one stage to another. The circuit characteristics are poorly defined and the manufacturing output is affected adversely.